Cardiac function management systems are used to treat arrhythmias and other abnormal heart conditions. Such systems generally include cardiac leads, which are implanted in or about the heart, for delivering an electrical pulse to the cardiac muscle, for sensing electrical signals produced in the cardiac muscle, or for both delivering and sensing.
During the cardiac lead placement procedure, it often becomes necessary and/or desirable to inject a contrast agent in the vicinity of the coronary sinus and then to form an image of the coronary sinus and surrounding vasculature in order to identify an appropriate vessel for lead placement. For example, a physician may perform a venogram procedure in which a radiopaque contrast agent is injected in the vicinity of the cardiac sinus, and then an X-ray image of the cardiac sinus is then taken. One difficulty physicians face when injecting a contrast agent in this manner is that retrograde blood flow tends to prematurely disperse the contrast agent such that the images of the desired blood vessels lack sufficient clarity for a physician to sub-select an appropriate vessel for lead placement. This contrast agent dispersion problem is particularly noticeable in the coronary sinus, which has a relatively large diameter and consequently passes a relatively high volume of blood.
Physicians face similar difficulties when injecting substantially transparent fluids (e.g., saline or dextrose) prior to light or ultrasound imaging of the vessel, and/or prior to subjecting a vessel to photodynamic and/or RF/electrical therapy. Such transparent fluids are used to provide an improved pathway or window for energy exposure, but may be carried away prematurely by blood flow. Further difficulties are faced by physicians injecting therapeutic agents for intravascular treatment of a condition. Typically, the therapeutic agent should be maintained in a specific location or region for at least a minimum time period. However, blood flow tends to carry the therapeutic agent away from the desired site prematurely.
There is a need in the art for a device adapted to occlude blood flow in a vessel to help maintain an injected substance at a target site in the vessel. There is a further need for a device which deploys readily and reliably.